1. Technical Field
The present invention relates to a sensor for detecting an edge of a printing medium and to a printer incorporating the same.
2. Related Art
Japanese Patent Publication No. 2001-247225A (JP-A-2001-247225) discloses an ink jet printer. The ink jet printer transports a printing medium such as paper on a sheet feeding tray to a printing region facing a printing head. Accordingly, printing by ink is performed on the paper by ejecting ink from the printing head.
In the printer disclosed in JP-A-2001-247225, for transport control of a printing medium, such as paper, it is necessary to recognize a position of the printing medium to be transported on a sheet transporting path.
For example, the printer needs to recognize presence/absence of the paper in the printing region so as to prevent ink from being ejected from the printing head in a state where paper does not exist in the printing region.
Besides, for example, the printer reduces the amount of sheet feeding pitch when the trailing end of the paper is printed or performs various controls for suppress ink from being ejected outside the paper. For these controls, it is necessary to recognize the position of the edge of the paper within the printing region.
In particular, when the sheet feeding speed increases or the sheet feeding pitch increases in order to increase the number of print pages per unit time, the edge of the paper to be transported to the printing region facing the recording head needs to be accurately and rapidly detected. When the accurate position of the edge of the paper to be transported is detected more rapidly, it is possible to increase the number of print pages per unit time.